OFETs, or more generally organic/polymer molecular electronics and devices, have been envisioned as a viable alternative to more traditional, mainstream thin-film transistor (TFT) based on inorganic materials. The processing characteristics and demonstrated performance of OFETs suggest that they can be competitive for existing TFT applications. Miniaturisation of the OFET structure is important for OFET applications as it increases the device density and decreases its power consumption. It also provides the best scaling factors for improved OFET performance, non-limiting examples of which include increased drain current and reduced modulation voltages. Miniaturised OFETs may enable organic transistors to compete with high-end applications of inorganic transistors.
However, the practical implementation of OFETs in electronic applications will ultimately be decided by the ability to produce devices and circuits at a cost that is significantly below that needed to manufacture conventional electronic circuits based on, for example, silicon. Although the cost of the organic materials used in most thin-film devices is low, the materials cost rarely determines that of the end product in electronics, where fabrication and packaging costs typically dominate. Hence, the successful application of OFETs will depend on capturing its low-cost potential through the innovative fabrication of devices on inexpensive, large-area substrates. This suggests that conventional semiconductor device fabrication technologies need to be adapted to handle large-area, flexible substrates spanned by organic macroelectronic circuits, and to be compatible with the physical and chemical properties of the organic compounds used.
Several methods have been used to fabricate OFETs, including screen printing, photolithography, dip coating and jet printing. For high-throughput production, dip coating is not feasible for making large area coverage OFET-based devices. Screen-printing and soft lithography printing have been explored for the fabrication of OFETs, but the former technique is limited to relatively large features (>100 μm) and the layer-to-layer registration of the latter has not been demonstrated to be better than 50 μm. Jet printing is an alternative technique for all printed OFETs. However, the smallest features in reported works are about 25 μm. There is no report of mass manufacturing technology for low micron (less than 10 μm) and nano scale OFETs. As outlined earlier, miniaturisation of the structure of an OFET is critical for its applications.